Plants synthesize many diverse small molecules that affect function of the mammalian central nervous system, making them crucial sources therapeutics for neurological disorders. A notable portion neuroactive phytochemicals are lysine-derived alkaloids, but mechanisms by which plants produce these compounds have remained largely unexplored. To better understand how metabolites, we focused on biosynthesis Lycopodium alkaloids produced club mosses, a clade used traditionally as herbal...

Abstract Plants synthesize numerous alkaloids that mimic animal neurotransmitters 1 . The diversity of alkaloid structures is achieved through the generation and tailoring unique carbon scaffolds 2,3 , yet many neuroactive belong to a scaffold class for which no biosynthetic route or enzyme catalyst known. By studying highly coordinated, tissue-specific gene expression in plants produce Lycopodium 4 we identified an unexpected biosynthesis: neofunctionalized α-carbonic anhydrases (CAHs). We...

Three new indole alkaloids (1−3), named grandilodines A−C, and five known ones were obtained from the Malayan Kopsia grandifolia. The structures established using NMR MS analyses and, in case of 1 2, confirmed by X-ray diffraction analyses. Alkaloids 1, 3, lapidilectine B (8) found to reverse multidrug resistance vincristine-resistant KB cells.

Two new monoterpene indole alkaloids, characterized by previously unencountered natural product skeletons, viz., arborisidine (1), incorporating indolizidine and cyclohexanone moieties fused to an unit, arbornamine (2), unprecedented 6/5/6/5/6 "arbornane" skeleton (distinct from the eburnan or tacaman skeleton), were isolated a Malayan Kopsia arborea. The structures of alkaloids determined based on analysis NMR MS data. Possible biogenetic pathways these common pericine precursor (3) are presented.

Eight new indole alkaloids (1–8) belonging to the rhazinilam–leuconolam–leuconoxine group, in addition 52 other alkaloids, were isolated from stem-bark extract of Leuconotis griffithii, viz., nor-rhazinicine (1), 5,21-dihydrorhazinilam-N-oxide (2), 3,14-dehydroleuconolam (3), and leuconodines A–E (4–8). The structures these determined using NMR MS analyses some instances confirmed by X-ray diffraction analyses. Alkaloids 1, 5, 7 showed only moderate weak cytotoxicity toward KB cells (IC50...

Six new indole alkaloids, viz., cononusine (1, a rare example of an iboga–pyrrolidone conjugate), ervaluteine (2), vincamajicine (3), tacamonidine (4), 6-oxoibogaine (5), and N4-chloromethylnorfluorocurarine chloride (6), two vobasinyl-iboga bisindole ervatensines A (7) B (8), in addition to other known were isolated from the stem-bark extract Malayan Tabernaemontana corymbosa. The structures these alkaloids established on basis NMR MS analyses and, one instance (7), confirmed by X-ray...

A total of 20 new indole alkaloids comprising mainly oxidized derivatives macroline- (including alstofonidine, a macroline incorporating butyrolactone ring-F), pleiocarpamine-, and sarpagine-type were isolated from the bark leaf extracts Alstonia angustifolia. The structures relative configurations these determined using NMR MS analyses in some instances confirmed by X-ray diffraction analyses. Alkaloids 3, 7, 35, 41 showed moderate to weak activity, while 21 strong activity reversing...

Ten new indole alkaloids (1–10) comprising five ibogan, two aspidosperman, one vincamine, and bisindole alkaloids, in addition to 32 known were isolated from the stem-bark extract of a Malayan Tabernaemontana corymbosa. The structures these determined based on analysis NMR MS data and, instances (1, 3, 5, 6, 8), confirmed by X-ray diffraction analysis. Two iboga conodusines B (2) C (3), iboga-containing tabernamidine (10) are notable for presence an α-substituted acetyl group at C-20 carbon...

Seven new indole alkaloids of the Strychnos type, leuconicines A−G (1−7), and a eburnan alkaloid, (−)-eburnamaline (8), were isolated from stem-bark extract two Malayan Leuconotis species. The structures these established using NMR MS analysis in case 8 also by partial synthesis. Alkaloids 1−5 reversed multidrug resistance vincristine-resistant KB cells.

Seven new indole alkaloids (1-7) comprising four vobasine, two tacaman, and one corynanthe-tryptamine bisindole alkaloid were isolated from the stem-bark extract of a Malayan Tabernaemontana. Two vobasine (1, 3), as well 16-epivobasine (15) 16-epivobasenal (17), showed appreciable cytotoxicity toward KB cells (IC50 ca. 5 μg/mL). The structure known Tabernaemontana tronoharine (8) was revised based on newly acquired NMR data, X-ray diffraction analysis.

Tengerensine (1), isolated as a racemate and constituted from pair of bis-benzopyrroloisoquinoline enantiomers, tengechlorenine (2), purified scalemic mixture chlorinated phenanthroindolizidine were the leaves Ficus fistulosa var. tengerensis, along with three other known alkaloids. The structures 1 2 determined by spectroscopic data interpretation X-ray diffraction analysis. enantiomers separated chiral-phase HPLC, absolute configurations (+)-1 (−)-1 established via experimental calculated...

Eleven new indole alkaloids (1–11) comprising seven aspidofractinine and four eburnane alkaloids, were isolated from the stem-bark extract of Kopsia pauciflora occurring in Malaysian Borneo. The include a ring-contracted, an additional ring-fused, paucidactine regioisomer, two paucidactine, one kopsine alkaloid. structures several these also confirmed by X-ray diffraction analyses. bisindole isolated, norpleiomutine kopsoffinol, showed vitro growth inhibitory activity against human PC-3,...

Two new indole alkaloids, voatinggine (1) and tabertinggine (2), which are characterized by previously unencountered natural product skeletons, were isolated from a Malayan Tabernaemontana species. The structures absolute configuration of these alkaloids determined using NMR MS analysis, X-ray diffraction analysis. A possible biogenetic pathway to novel an iboga precursor, via common cleavamine-type intermediate, is presented.

Several transformations of the seco Aspidosperma alkaloid leuconolam were carried out. The based-induced reaction resulted in cyclization to yield two epimers, major product corresponding optical antipode a (+)-meloscine derivative. structures and relative configuration products confirmed by X-ray diffraction analysis. Reaction epi-leuconolam with various acids, molecular bromine, hydrogen gave results that indicated structure alkaloid, previously assigned as epi-leuconolam, was incorrect....

Examination of the EtOH extract Malayan Tabernaemontana corymbosa resulted in isolation three new alkaloids, viz., cononuridine (1), an unusual hexacyclic, iboga-derived, monoterpenoid indole characterized by contraction tetrahydroazepine C-ring and incorporation additional isoxazolidine ring, taberisidine (2), a seco-corynanthean alkaloid, conofolidine (3), Aspidosperma-Aspidosperma bisindole that showed pronounced vitro growth inhibitory activity against array human cancer cell lines,...

Nine new alkaloids, eugeniinalines A–H (1–8) and (+)-eburnamenine N-oxide (9), comprising one quinoline, six indole, two isogranatanine were isolated from the stem-bark extract of Malayan Leuconotis eugeniifolia. The structures absolute configurations these alkaloids established based on analysis spectroscopic data, GIAO NMR calculations, DP4+ probability analysis, TDDFT-ECD method, X-ray diffraction analysis. Eugeniinaline A (1) represents a pentacyclic quinoline alkaloid with 6/6/5/6/7...

A total of 25 alkaloids were isolated from the leaf and stem-bark extracts Alstonia spatulata, which five are new strychnan type (alstolucines A−E, 1−5) other, a alkaloid secoangustilobine (alstolobine A, 6). The structures these established using NMR MS analysis and, in case alstolucine B (2), also confirmed by X-ray diffraction analysis. reinvestigation stereochemical assignment scholaricine (13) analyses indicated that configuration at C-20 required revision. Alkaloids 1, 2, 6, 7, 9, 10,...

Four new linearly fused bisindole alkaloids, lumutinines A–D (1–4), were isolated from the stem-bark extract of Alstonia macrophylla. Lumutinines A (1) and B (2) represent first examples linear, ring A/F-fused macroline–macroline-type bisindoles, while C (3) D (4) constituted union macroline sarpagine moieties. reinvestigation stereochemical assignment alstoumerine (8) by NMR X-ray diffraction analyses indicated that configuration at C-16 C-19 required revision.

Reexamination of the absolute configuration recently isolated eburnane alkaloids from Malaysian Kopsia and Leuconotis species by X-ray diffraction analysis ECD/TDDFT has revealed existence biosynthetic enantiodivergence. Three different scenarios are discerned with respect to composition enantiomeric in these plants: first, where new congeners possess same C-20, C-21 configurations as common (eburnamonine, eburnamine, isoeburnamine, eburnamenine) occurring plant; second, opposite or compared...

A systematic study of the electrochemical oxidation 1,2-diarylalkenes was carried out with focus on detailed product studies and variation type as a function aromatic substitution. reinvestigation 4,4'-dimethoxystilbene under various conditions first out, all products formed were fully characterized quantitated. This followed by investigation effect substitution nature distribution products. The substituents found to fall into three main categories, viz., substrates in which position gave...

A new monoterpene indole alkaloid characterized by an unprecedented pentacyclic cage skeleton, arboridinine (1), was isolated from a Malaysian Kopsia species. The structure and absolute configuration of the were determined based on NMR, MS, X-ray diffraction analysis. possible biogenetic pathway pericine precursor is presented.